The Markers Core will serve as a resource for the development and optimization of established as well as new methods for measuring research endpoints in the individual projects. In conjunction with the Human Tissue Procurement Service and the Biometry Cores, the Markers Core will develop and implement appropriate sample collection, tracking, storage and preparation procedures for human material collected during the course of this proposal. It is essential that biological samples be collected and stored appropriately to achieve good quality assay results. The Markers Core will serve as a resource for assay development, analysis and quantitation of immunohistochemical procedures in support of each project. Endpoints will include markers of cell proliferation, apoptosis, as well as potential prognostic and/or predictive factors under evaluation in the SPORE proposal. The prognostic and/or predictive factors will Include assays for genetic variability (Project 1) COX-2 and NOS2 (Project 2), MUC-1 (Project 3), thioredoxin (Project 4) and c-myc (Project 5). The Tissue Service will be essential to the Markers Core for pathologic assessment of GI tissues and for obtaining tissue sections required for assays. The Markers Core will also work closely with the Biometry Core to maintain and evaluate quality control measures. Quality control measures will be an important component of the Markers Core and will be established for each assay. Historically, the Core has done a ten percent repeat of study samples to assess reproducibility.